Couldn’t be a problem of the tray icon being hidden? The tray icon being hidden is not the same as Avast not running at all.

Look for a cleared area on the task bar (meaning, not over a current program button). Right click on a clear area of the task bar and select “properties”. Look for the option to “hide inactive icons in the notification (tray) area” (it might be under a different tab of that “properties” window). UNcheck that option.

This should allow all your icons in your tray area to be displayed, even if the program has not been active for a long time. Is now Avast tray icon being displayed?